This project is a study of the basic physiology of the inner ear and of the causes of deafness. The basic purpose is to apply an interdisciplinary approach to these studies by an interchange of ideas and combination of techniques provided by a staff of scientists trained in different specialities. The Kresge Hearing Research Institute is in a separate building of the Medical Center and consists of several unique laboratories with specialized personnel, techniques and equipment devoted to this project: Biochemistry, Anatomy and Histology, Animal Behavioral, Electrophysiology, Experimental Pathology, Microcirculatory, Neurophysiology and Psychoacoustics. The distinct characteristics of these laboratories within one facility is the intermingling of staff and the application of the various technical approaches to common problems. In addition to the study of the normal processes of hearing, the laboratories are investigating how toxins of various sorts (drugs, viral) affect the ear and how the resulting hearing loss might be prevented. Also being investigated are the cause and prevention of temporary and permanent threshold shifts due to noise, vascular changes, presbycusis and congenital factors.